1. Field of the Invention
The present invention relates to a waterproof slide fastener having waterproof property in which the entire front and rear surfaces of a woven or knitted fastener tape are covered with elastomer to complete a fastener tape having waterproof property, and then, fastener elements are injection molded on side edges of the fastener tapes by using thermoplastic resin.
2. Description of the Related Art
Conventionally, according to Japanese Utility Model Publication No. 59-42893, there has been known a slide fastener formed into a configuration which prevents its fastener chain 101 from being broken, the fastener chain 101 being formed by attaching injection molded type fastener elements 103 to a fastener tape 102, as shown in FIG. 15. In this slide fastener, a core thread 140 is attached to a side edge of the fastener tape 102, and through holes 108 going through between front and rear surfaces are provided on which the fastener elements 103 are attached. The part of leg portions 114 of the fastener element 103 and a tongue piece extending from the rear end of the leg portion 114 are attached to the through hole 108 such that the through hole 108 is covered therewith. In addition, the side face of the tongue piece provided on the end portion of the leg portion 114 is provided with a bend restricting piece 130 in a state in which it keeps contact with the fastener tape 102 with a larger width than that of the leg portion 114 in order to prevent the chain from being cracked when the fastener chain 101 is bent in the longitudinal direction.
Additionally, according to Japanese Patent Laid-Open Publication No. 2005-237577, there has been known another slide fastener having waterproof property as shown in FIG. 16. In this slide fastener, both front and rear surfaces of a woven or knitted fastener tape 202 are covered with thermoplastic elastomer to complete a fastener tape 202 having waterproof property. Through holes 208 going through between front and rear surfaces are provided at each fastener element attachment position on the edge portion of the fastener tape 202. Fastener elements 203 each formed of a coupling head 210, a neck portion 212, a leg portion 214 and a tongue piece 216 are attached to the side edge of the fastener tape 202 by injection molding using thermoplastic resin. The through holes 208 are covered with the leg portions 214 of the fastener elements 203, and the leg portions 214 on the front and rear surfaces are joined by a connecting portion 215 through the through hole 208.
The slide fastener shown in FIG. 15 is an ordinary type slide fastener having no water-tightness or airtightness. In order to attach fastener elements 103 firmly to the side edge of the fastener tape 102 by injection molding using thermoplastic resin, a core thread 140 is attached to the side edge of the fastener tape 102, through holes 108 are made in the side edge of the fastener tape 102, and fastener elements 103 are molded at positions in which the through holes 108 exist. In order to prevent the fastener chain 101 from being broken, bend restricting pieces 130 having larger width than that of the leg portion 114 and projecting to the side are molded on the tongue piece formed at the rear end of the leg portion 114 of the fastener element 103 such that the bend restricting pieces 130 are joined to the fastener tape 102. As a result, when the fastener chain 101 is bent in the longitudinal direction, the bend restricting pieces 130 keep firm contact with each other, so that a large load is applied to the bend restricting pieces 130 joined to the fastener tape 102. Consequently, the fastener elements 103 turn unstable, thereby getting loose.
In the waterproof slide fastener shown in FIG. 16, the front and rear surfaces of the fastener tape 202 are covered with thermoplastic elastomer to complete a fastener tape 202 having waterproof property, through holes 208 going through between the front and rear surfaces are provided in the side edge of the fastener tape 202, and the through holes 208 are covered with the leg portions 214 of the fastener elements 203. When a load is applied in the longitudinal direction of the fastener chain, the through holes 208 are exposed out of the fastener elements 203, thereby making it difficult to maintain water-tightness. Particularly, when the size of the fastener element 203 is reduced, the through hole 208 cannot be reduced in diameter easily. The present invention is achieved by improving this point.